Shelf



FIG. 1 is a front perspective view of the shelf according to the invention;

FIG. 2 is a front elevational view of the shelf;

FIG. 3 is a back elevational view of the shelf;

FIG. 4 is a top view of the shelf;

FIG. 5 is a bottom view of the shelf; and,

FIG. 6 is an end view of the shelf.

The broken line showing of structure is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a shelf, as shown and described. 